The present invention relates generally to the field of electrosurgery, and more particularly to surgical devices and methods which employ high frequency electrical energy to remove fatty tissue. The present invention also relates to methods and apparatus for electrosurgical treatment of skin for contraction of collagen fibers within the skin. The present invention also relates to methods and apparatus for electrosurgical induction of collagen deposition in the dermis.
Suction lipectomy, commonly known as liposuction or lipoxheresis, is a well known surgical procedure used for sculpturing or contouring the human body to increase the attractiveness of its form. In general, the procedure involves the use of a special type of curette or cannula which is coupled to an external source of suction. An incision is made in the target area and the fatty tissue is essentially vacuumed from the patient's body. This procedures has its disadvantages, however, because the fat is relatively difficult to separate from the surrounding tissue. Such separation often causes excessive bleeding and damage to adjacent tissue or muscles. A further problem is that the surgeon must be careful not to allow the suction to remove or injure any desirable tissues, such as muscle, blood vessels, skin, subcutaneous tissues and the like. In addition, it is often difficult to maintain constant suction without stopping to clean tissue fragments from the cannula. Normally, the surgeon attempts to compensate for this problem by rapidly moving the cannula within the cavity, and even periodically withdrawing it to allow the fat to move through the cannula. This causes further trauma and collateral damage to surrounding muscle, tissue and other body structures.
In an effort to resolve some of the drawbacks with conventional liposuction, ultrasonic probes for vibrating and aspirating adipose tissue have been developed. The ultrasonic vibrations physically melt the fatty tissue so that it can be emulsified and aspirated through the probe. These ultrasonic probes have reduced the physical exertion required by the surgeon to remove fatty tissue, increased the speed of the operation and reduced the collateral damage created at the incision point. One problem with these probes, however, is excess heat generation at the distal tip of the ultrasonic probe. For example, when the probe has been inserted into the fatty tissue near the skin or the peritoneum, resistance can be met, which increases the wattage at the tip of the probe. The heat generated at the tip of the probe from the increased wattage may be in excess of the heat required for melting the fatty tissue. This excess heat results in burning of tissue, collateral damage to muscles or blood vessels and even penetration of membranes such as the skin or the peritoneum.
RF energy has also been used in liposuction procedures to remove fatty tissue. In particular, microwave and monopolar RF devices have been used to heat and soften fatty tissue so that the tissue can be more readily detached from the adjacent tissue with a suction instrument. Similar to ultrasonic energy, however, current microwave and monopolar RF devices have difficulty controlling excess heat generation at the target site, resulting in undesirable collateral tissue damage. For example, conventional electrosurgical cutting devices typically operate by creating a voltage difference between the active electrode and the target tissue, causing an electrical arc to form across the physical gap between the electrode and tissue. At the point of contact of the electric arcs with tissue, rapid tissue heating occurs due to high current density between the electrode and tissue. This high current density causes cellular fluids to rapidly vaporize into steam, thereby producing a “cutting effect” along the pathway of localized tissue heating. This cutting effect generally results in the production of smoke, or an electrosurgical plume, which can spread bacterial or viral particles from the tissue to the surgical team or to other portions of the patient's body. In addition, the tissue is parted along the pathway of evaporated cellular fluid, inducing undesirable collateral tissue damage in regions surrounding the target tissue site.
Moreover, monopolar electrosurgery methods generally direct electric current along a defined path from the exposed or active electrode through the patient's body to the return electrode, which is externally attached to a suitable location on the patient's skin. In addition, since the defined path through the patient's body has a relatively high electrical impedance, large voltages must typically be applied between the active and return electrodes to generate a current suitable for cutting or coagulation of the target tissue. This current, however, may inadvertently flow along localized pathways in the body having less impedance than the defined electrical path. This situation will substantially increase the current flowing through these paths, possibly causing damage to or destroying tissue along and surrounding this pathway.
The skin is the largest organ of the human body, having a weight of approximately six pounds in the adult. The skin has important functions, including: protection from injury and infection; regulation of body temperature; and storage of fat, water, and vitamin D. The skin has a layered structure comprising the outer epidermis, the dermis, and the inner subcutis. The epidermis is a relatively thin layer. The dermis is a relatively thick layer containing the protein collagen, which provides strength and resilience to the skin. The subcutis lies below the dermis and consists of a network of collagen and fat cells.
Following an electrosurgical or conventional liposuction procedure, a pocket may be formed beneath the skin whence adipose tissue was removed, wherein the pocket is overlaid by an excessive area of skin or by a region of excessively loose skin. There is a need for apparatus and methods for treating the skin in a region having undergone liposuction, for the purpose of shrinking and/or tightening the skin in that region. There is a further need for shrinking and tightening the skin following or during face-lift and neck-lift cosmetic procedures. There is also a need for apparatus and methods for electrosurgically treating the skin in order to reduce or remove unwanted wrinkles in the skin.